Yes. Epic released the original Unreal and Unreal Tournament for free, permanently. This one is not a grey area.
Epic made the original Unreal and Unreal Tournament available free of charge, and the community at OldUnreal maintains installers and patches that run on modern systems with working multiplayer.
It is a rare case of a major publisher doing the generous thing. What you get is the complete game with bot matches, the full weapon set and still-active community servers.
If you want arena shooting of that era without touching anything legally shaky, this is the front door.